Background: The Implementation Research Institute (IRI) provides two years of training in mental health implementation science for 10 new fellows each year. The IRI is supported by a National Institute of Mental Health (NIMH) R25 grant and the Department of Veterans Affairs (VA). Fellows attend two annual week-long trainings at Washington University in St. Louis. Training is provided through a rigorous curriculum, local and national mentoring, a ‘learning site visit’ to a federally funded implementation research project, pilot research, and grant writing. Methods: This paper describes the rationale, components, outcomes to date, and participant experiences with IRI. Results: IRI outcomes include 31 newly trained implementation researchers, their new grant proposals, contributions to other national dissemination and implementation research training, and publications in implementation science authored by the Core Faculty and fellows. Former fellows have obtained independent research funding in implementation science and are beginning to serve as mentors for more junior investigators. Conclusions: Based on the number of implementation research grant proposals and papers produced by fellows to date, the IRI is proving successful in preparing new researchers who can inform the process of making evidence-based mental healthcare more available through real-world settings of care and who are advancing the field of implementation science.